Ousted Nissan chairman Carlos Ghosn will face a further accusation of under-reporting his salary by about four billion yen ($35.5 million) over the last three years, Japanese media reported Wednesday.
Tokyo prosecutors plan to "rearrest" the business tycoon along with his right-hand man and former Nissan representative director Greg Kelly by Monday, according to major media including the Nikkei and the Mainichi newspapers.
If confirmed, the new allegation would come on top of an existing accusation that the pair conspired to understate Ghosn's pay by some five billion yen in official filings during the five years up to March 2015.
Japanese prosecutors declined to comment on the reports regarding the duo, who were arrested on November 19 and remain in custody.
In Japan, a suspect can be kept in custody and "rearrested" several times on different allegations, a system that has sparked some criticism in the international media.
They have yet to be officially charged with any crime and deny the allegations, reportedly insisting they had checked with authorities about the way they declared the money.
In a move that stunned the business world, Ghosn was arrested at a Tokyo airport on November 19 on suspicion of under-declaring his income.
Authorities then had 22 days to question him over these suspicions.
That period runs out on Monday, meaning they are likely to rearrest him over the new allegations, giving them a further 22 days to interrogate the tycoon.
He is therefore likely to remain in detention until early next year at least.
Japan had long celebrated Ghosn as a charismatic business leader who saved Nissan from the brink of failure and rebuilt it as a money-making subsidiary of Renault.
But since his unexpected arrest, he has been removed from the boards of Nissan and Mitsubishi Motors - the third company in the alliance that outsold all its rivals last year.
Nissan has begun a process of choosing Ghosn's successor, with the final decision expected on December 17.